FGFR1 and breast neoplasm: Furthermore, several growth factor receptors, such as epidermal growth factor receptor (EGFR), insulin-like growth factor 1 receptor (IGF-1R) and fibroblast growth factor 1 receptor (FGFR1), which are involved in the EMT process, are highly expressed in ER- breast tumor cells, supporting the link between EMT and insensitivity to endocrine therapy [2].